<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>外边距重叠</title>
        <style type="text/css">
            .outer { background-color: #1e9fff ; margin: 100px ; border: 1px solid transparent ; }
            .inner { background-color: #FFFF00 ; margin: 50px ; height: 100px ; }
        </style>
    </head>
    <body>

        <div class="outer">
            <div class="inner"></div>
        </div>
        
    </body>
</html>